Process of smelting iron oxids.



, HORACE w. LASH, or CLEVELANDPOHIO.

PROCESS OF SMELTING IRON OXIDS.

I Specification of Letters Patent.

Fatented June 15, 1909.

Application filed September 12, 1907. Serial No. 392,461.

To all whom it may concern:

Be it known that I, HORACE W. LASH, a

citizenof the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Processes of smelting Iron Oxids, of which the following is, a full, clear, and exact description.

My invention relates to the reduction of iron oxids either into finished steel or into a partially refined condition suitable for the making of castings or finished iron or steel by further treatment.

In carrying out my invention I prepare a smelting mixture comprising finely ground or comminuted oxid of iron, such as iron sand or scale, and finely divided cast or pig iron and a carbonaceous material as coke. For the preparation of this mixture the several mgredients may be separately ground or, if preferred receive their final comminution during the mixin process by being ground together during t 1e mixing.

The iron oxid which I employ in the smelting mixture may be obtained from any of the suitable sources,- such as the sand ores of the'St. Lawrence or New Zealand. The essential thing is that the iron oxid shall be in a finel divided condition in the mixture. The fine y divided cast or pig iron of the smelting mixture maybe obtained from any suitable source, suchforexample as iron turnings or borings, but it is necessary that this portion of the mixture shall be distinctly of that quality of iron commonly designated as cast or pig iron, as distinguished from the ordinary run of scrap, wrought iron or steel, since it is im ortant that it contain a high percentage 0 metalloids or easilyoxidizable metals, such as manganese, capable of unit ing with the oxygen of the iron oxid.

The carbonaceous material above mentioned as forming part of the mixture, is

preferably in the form of ordinary coke, and 1s finely ground, as are the other portions of the char e mixture.

In ad ition to the above mentioned ingredients, I find it advantageous in man cases to add to the smelting mixture 3. small pro ortion of readily combustible material, sue as crushed bituminous coal or sawdust. This addition is for the purpose of rendering the mass porous, an end which is easily accomplished owing to the combustion of the sawdust taking lace at an early stage of the vprocess, thus eaving unfilled 1 interstices throughout the mass. The carbon of the sawdust coats the particles of the iron oxid,

and probabl for this reason assists in the reduction. nary kind, such as lime and fluorspar varied to suit-the different grades of ore. It is,

however, customary to add fluxes to smelt ing mixtures, and I do not claim any novelty for this feature. If it is found desirable to handle the mixture in the form of briquets, a suitable binder, such as coal tar pitch, may be employed. This mixture may be varied as to the ro ortions ofits constituent elements. 'fire Following, however, I find to be an effective mixture when used in the smelting process below described Crushed limestone The exact percentages above named need not be followed. In fact different operators will always be found to use different propor tions, forreasons of their own, on account of individual notions as to the manner in which the heat should be handled. The general characteristics of the mixture, however,.will

be found to be set forth in my U. S. patent thereon No. 862,978, August 13, 1907. In the smelting of this mixture by the process forming the subject of this application for patent, I Iplace a certain quantity of pig iron upon the i the type commonly designated as the open hearth, which receives its heat from above,

This pig iron may be in the form of cold pigs or any other solid form extending over the sole of the furnace and preferably up near the edges of the bowl shaped hearth. The pig metal, however, may be molten in condition instead of solid, but the solid metal is preferable in most cases by reason of it being more easily handled and distributed. The smelting mixture which I have above described is then charged into the furnace on top of the layer of pig iron and the charge raised to smelting heat. If, for any reason, the smelter desires to make use of scrap metal, he-ma' charge this into the furnace in addition to t e afore-- said smelting mixture, as its use is not inconsistent with my procedure and it ordinarily accumulates around most steel plants. qAs heat is now applied to the charge, the smeltmay also add flux of the ordi earth of a metallurgical furnace of ing mixture will ultimately be observed to sweat, a parently, on the surface and the charge wil about the same time, settle somewhat, so, that in the event the full furnace charge has not been added at the beginning of the operation the remaining portion may be subsequently thrown in. As the mass rises in temperature, and before the smelting temperature of the mixture is reached, the pig metal in the lower portions of the furnace will, if solid, fuse and become liquid, and for the purpose of facilitating and quickening" this liquefaction the cold pig metal used to form the lower portion of the charge may be spread, as above stated, up around the edges of the furnace hearth close to the surface so that the heat of the flamemay be transmitted to it quickly. Also, solid pig may be distributed in pockets in the mass of the smelting mixture where the chargeis very thick, the pigs thus distributed fusing and trickling down through the mass and thus facilitating the early reduction of the smelting mixture. As soon the pig metal in the bottom of the charge becomes 5 molten, the smelting mixture resting thereon is rapidly dissolved by the molten bath, the necessary reactions taking place much more readily than if the smelting mixture were subjected to heat without contact with such a metallic-bath.

While the smelting mixture may be s1nclt* ed alone under certain conditions, to an ad vantage, and the reduction will take place as set forth in my prior patent above mentioned, the present procedure involving the use of solid or molten pig iron in the lower part of the charge is of the greatest advantage in practical operation;

Y While the continued application of heat to the mixture would, as stated, eventually result in the reduction of the oxids, nevertheless, the obtaining of a bath of the pig metal capable of dissolving .the adjacent particles of the smelting mixture and itself assisting through its carbon and other metalloids, in

' the reduction, quickens the process to a great extent. This procedure is effective, further, b reason of the fact that while the reduction 5 the oxid 1n the smelting mixture is taking place in the lower portion of tl'ieitharge, the

molten bath containing its high percentage (if carbon is protected against the oxidizing atmosphere above the charge by the overlying smelting mixture itself, whichas the rocess proceeds, floats somewhat like an island in the bath, receiving the heating flame directly. The oxidizing atmos here over the charge, will take out consider-a is of the carbon from the surface of the charge mixture, which surface will, under the combined influence of the heat and the ox gen, become reduced to the condition of a most pure iron, but the carbon losses in the way are small. It will thus be seen that not only is the process of smelting a'rapid one, but the carbon of the bath, whlch is formed during the smelting process, is effectually protected so that when the reducing process is com pleted the bath will be still fusible, by reason of being protected against any material loss of its carbon due to the oxidizing flame. The bath finally obtained may be refined in the furnace or tapped, according to the desire of the smelte a ll found inpractice that an economical proportion of materials to be used in forming the charge may be produced by employing enough of the sme ting mixture to comprise about eighty per cent. of the total charge, the remaining twenty per cent. being made up of pig metal which is charged into the lower portion of the furnace. Of course, if scrap be added to the charge, the proportion will vary somewhat.

Having thus described my ii'ivention, I

claim:

1. A process of smelting iron oxids which involves charging into a furnace a smelting mixture containing finely divided oxid of iron, finely divided cast iron and carbonaceous material, and also disposing in said furnace a quantity of pig metal in proper man- I hereunto alfix my 

